From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DC1ADC76191 for ; Thu, 18 Jul 2019 14:12:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BC8EC20880 for ; Thu, 18 Jul 2019 14:12:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727791AbfGROMT (ORCPT ); Thu, 18 Jul 2019 10:12:19 -0400 Received: from mx1.redhat.com ([209.132.183.28]:39360 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726715AbfGROMT (ORCPT ); Thu, 18 Jul 2019 10:12:19 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 0BC5830860BC; Thu, 18 Jul 2019 14:12:19 +0000 (UTC) Received: from treble (ovpn-122-211.rdu2.redhat.com [10.10.122.211]) by smtp.corp.redhat.com (Postfix) with ESMTPS id BB5755ED3C; Thu, 18 Jul 2019 14:12:17 +0000 (UTC) Date: Thu, 18 Jul 2019 09:12:10 -0500 From: Josh Poimboeuf To: Paolo Bonzini Cc: Sean Christopherson , x86@kernel.org, linux-kernel@vger.kernel.org, Peter Zijlstra , Thomas Gleixner , Nick Desaulniers , Arnd Bergmann , Jann Horn , Randy Dunlap , Radim =?utf-8?B?S3LEjW3DocWZ?= Subject: Re: [PATCH v2 04/22] x86/kvm: Don't call kvm_spurious_fault() from .fixup Message-ID: <20190718141210.us7giumvgbgifvtv@treble> References: <64a9b64d127e87b6920a97afde8e96ea76f6524e.1563413318.git.jpoimboe@redhat.com> <65bbf58d-f88b-c7d6-523b-6e35f4972bf2@redhat.com> <20190718131654.GE28096@linux.intel.com> <1b891612-18e6-48ed-cfb5-05e8aca79dcb@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <1b891612-18e6-48ed-cfb5-05e8aca79dcb@redhat.com> User-Agent: NeoMutt/20180716 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.44]); Thu, 18 Jul 2019 14:12:19 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jul 18, 2019 at 03:18:50PM +0200, Paolo Bonzini wrote: > On 18/07/19 15:16, Sean Christopherson wrote: > >> Acked-by: Paolo Bonzini > >> > >> This has a side effect of adding a jump in a generally hot path, but > >> let's hope that the speculation gods for once help us. > > Any reason not to take the same approach as vmx_vmenter() and ud2 directly > > from fixup? I've never found kvm_spurious_fault() to be all that helpful, > > IMO it's a win win. :-) > > Honestly I've never seen a backtrace from here but I would rather not > regret this when a customer encounters it... In theory, changing the "call kvm_spurious_fault" to ud2 should be fine. It should be tested, of course. I would defer to Sean to make the patch on top of mine :-) -- Josh